Synthesis of Zr-containing BEC-type germanosilicate with high Lewis acidity

Abstract

Zr-containing germanosilicates with BEC structure have been synthesized using three different procedures, involving i) direct treatment of parent Ge-BEC material with ZrOCl2 in 0.01 M HCl aqueous solution; ii) direct treatment with ZrOCl2 in DMSO; and iii) partial stabilization of BEC-structure via solvothermal treatment with TEOS followed by treatment with ZrOCl2 in DMSO. The stability of the materials and the incorporation of Zr into the zeolite framework are verified by XRD, NMR, FTIR and UV–vis spectroscopic techniques. The results show that the stabilization of BEC germanosilicate with TEOS before modification with Zr yields the material with high thermal stability and Lewis acidity. The Lewis acid sites of such material exhibit high catalytic activity and selectivity in the MPVO reaction of levulinic acid with 1,4-butanediol comparable to those of Zr-BEA obtained by traditional hydrothermal synthesis in fluoride media. However higher content of such sites can be achieved by post-synthesis treatment of Ge-BEC.